Utilizing an organotypic in vitro system, which shares many characteristics with lungs in whole animals, we plan to examine the toxicity of various gaseous and particulate air pollutants on the histotypic organization of the cultures and on the synthesis, storage and secretion of the pulmonary surfactant by the type II alveolar pneumonocytes. After demonstrating that certain ultrastructural, cytochemical and biochemical characteristics found in whole lung are also present in our organotypic systems, we will subject the system to pollutants and observe the changes. More specifically, we will monitor the effects of pollutants on surfactant production by determining the rates of incorporation of 14C-choline into saturated lecithin and the cytochemical distribution of esterases. Fine structure analysis will be by transmission and scanning electron microscopy.